INTRODUCTION: Olfactory neuroblastoma is a tumour of neural crest
origin arising from the olfactory neuroepithelium of the roof of the
nasal cavity and paranasal sinuses. It was first described by Berger and
Luc in the French medical literature. Less than 1000 cases have been
described in literature since 1924. Olfactory neuroblastoma represents
5-10% of sinonasal tumours and less than 1% of all malignant tumours and
has no sex predilection. It has bimodal age distribution occurring most
commonly in teenagers and in sixth decade of life. (1)

The symptoms of olfactory neuroblastoma include unilateral
progressive nasal obstruction, rhinorrhoea, epistaxis, anosmia and
headache. Extension of disease into orbit may result in proptosis,
diplopia and retrobulbar pain. However, patient often presents with non
specific symptoms resembling chronic sinusitis and therefore many cases
are diagnosed late with advanced disease. (1) Cervical lymph node
metastasis is most frequent but late (6 to 20% cases). Distant
metastasis is seen in 9 to 13% of patients and tends to involve bone,
lungs and liver. Local recurrence is relatively frequent (2-3years after
initial treatment).

It usually grows slowly but with locally invasive behavior. It
spreads through submucosal planes to the surrounding structures and
involves anterior cranial fossa destroying the cribriform plate with
propagation along the perineural spaces of olfactory nerves. Orbital
extension takes place through erosion of lamina papyracea.

Nasal endoscopy usually confirms an exophytic polypoid or sessile
mass arising from the superior portion of the nasal cavity. (1)

This tumour which can some times present with intracranial symptoms
is relatively slow growing and is considered to be radiosensitive.
Surgery followed by radiation therapy is the preferred treatment. (2)

CASE REPORT: A 35 year old male presented to us with complaints of
mass in left nasal cavity, nasal obstruction, nasal discharge, headache,
inability to close both eyes and occasional nasal bleeding of 15days
duration.

There was previous history of left sided nasal obstruction, left
nasal mass and nasal discharge of six months duration for which patient
was admitted in our ward and underwent nasal polypectomy 1 month before
the recent admission. There was no history of headache and inability to
close the eye at that time. HPE report of the resected mass was
suggestive of granuloma pyogenicum with dense lymphocytic infiltration
in stroma. The patient came again to us after 15 days of nasal
polypectomy with present complaints of mass in left nasal cavity, nasal
obstruction, nasal discharge, headache, inability to close both eyes and
occasional nasal bleeding for which repeat surgery was done and HPE
report was suggestive of olfactory neuroblastoma.

On examination nasal septum was deviated to right and reddish brown
mass was present in the left nasal cavity with blood present over it,
irregular surface and insensitive to touch. On posterior rhinoscopy,
mass was present on left chonae covered with slough. Proptosis of both
eyes was present. (L>R)

The tumor consists of large islands of small cells with
hyperchromatic nuclei showing a vesicular pattern and scanty cytoplasm.
Mitotic activity is brisk and areas of necrosis can be seen.
(Hematoxylin and eosin stain).

DISCUSSION: Olfactory neuroblastoma also called as
Esthesioneuroblastoma is a relatively uncommon intranasal tumour that
originates from the olfactory epithelium of the upper nasal cavity in
the region of cribriform plate. (3)

Distant and regional metastasis is present in 14 to 38% of cases at
the time of diagnosis and cervical lymph nodes, lungs and bone are the
most commonly involved sites. (4)

The hallmark of olfactory neuroblastoma is the formation of tumour
cells in to rosettes, pseudorosettes or sheets and clusters separated by
fibrovascular stroma. (1)

Electron microscopy and immunohistochemical studies are frequently
needed to establish the diagnosis. Olfactory neuroblastoma stains
strongly positive for a variety of neuroendocrine markers such as neuron
specific enolase, chromogranin and synaptophysin. The rosettes may be
surrounded by several spindle or stellate cells which stains positive
for S-100. (1)

It is well established that the degree of histopathological
differentiation is strongly correlated with the biological behaviour and
prognosis. Hyams et al. introduced four grades of differentiation based
on growth, architecture, mitotic activity, necrosis, nuclear
pleomorphism, rosette formation and fibrillary stroma. A higher grade in
the Hyams classification is associated with poorer prognosis.

STAGE FEATURES:
A Disease confined to the nasal cavity
B Disease confined to the nasal cavity and paranasal sinuses
C Disease beyond the nasal cavity and paranasal sinuses,
including involvement of cribriform plate, base of skull,
orbit or intracranial cavity
D With metastasis to cervical lymph nodes or distant
metastasis.

A CT scan will assess local invasion in to the adjacent bony
structures, particularly the cribriform plate and MR scan will assess
the extent of soft tissue invasion, particularly involvement of the
anterior cranial cavity and orbit. (1)

Craniofacial resection is the standard surgical approach for most
cases enabling en bloc resection with the cribriform plate. This has
been shown to improve overall survival as well as disease free survival.
Five year survival has been shown to improve from 37.5 to 82% with
craniofacial resection. However, despite macroscopic clearance there is
relatively high risk of locoregional recurrence of 10 to 30% and
therefore adjuvant therapies with radiotherapy with or without
chemotherapy have been explored. (1)

CONSENT: Written informed consent was obtained from the patient for
publication of this case report and accompanying images.

DOI: 10.14260/jemds/2014/2830

REFERENCES:

(1.) Stell and Maran's. Textbook of Head and neck surgery and
oncology, 5th Edition, Page 792-795.